Unlocking Diamond Secrets: How Inclusions Reveal Earth’s Deep History
Diamonds do more than sparkle—they hold tiny inclusions that act as time capsules, revealing conditions deep within the Earth. But to unlock their secrets, scientists must accurately determine the pressure at which the diamond formed. Traditional geothermobarometry assumes that stress relaxation in these inclusions happens in predictable ways, but is that really the case?
In this study, Bhanu Puhan et al put these assumptions to the test using advanced finite element models (XFEM) and cohesive zone models (CZM) to simulate how brittle fractures affect stress relaxation in olivine-in-diamond systems. Their models assumed dry conditions (no fluids) and elastic isotropy (uniform material properties).
Here’s what they found:
Inclusion shape and diamond strength determine when fractures start, but inclusion size and diamond toughnesscontrol how they grow.
Fractures relieve less stress than the elastic interaction between the diamond and the inclusion.
Inclusion shape doesn’t significantly impact stress relaxation from fractures.
Even under extreme assumptions (weaker and more fracture-prone diamonds), models still showed less stress relaxation than observed in real diamonds.
So, what’s missing? The findings suggest that in natural diamonds, other processes—like plastic deformation, preexisting defects, or fluids trapped in the host—play a big role in stress relaxation. To truly reconstruct a diamond’s history, researchers need more advanced numerical models that consider these additional complexities.
This study challenges old assumptions and brings us one step closer to decoding the deep-Earth processes recorded in diamonds!